EP0009450B1 - Détecteur de rayonnements gamma pour le contrôle d'aiguilles combustibles - Google Patents

Détecteur de rayonnements gamma pour le contrôle d'aiguilles combustibles Download PDF

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Publication number
EP0009450B1
EP0009450B1 EP79400652A EP79400652A EP0009450B1 EP 0009450 B1 EP0009450 B1 EP 0009450B1 EP 79400652 A EP79400652 A EP 79400652A EP 79400652 A EP79400652 A EP 79400652A EP 0009450 B1 EP0009450 B1 EP 0009450B1
Authority
EP
European Patent Office
Prior art keywords
gamma
scintillator
ray detector
detector
photomultipliers
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP79400652A
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German (de)
English (en)
French (fr)
Other versions
EP0009450A1 (fr
Inventor
Ange Aliotti
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique CEA
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Publication of EP0009450A1 publication Critical patent/EP0009450A1/fr
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Publication of EP0009450B1 publication Critical patent/EP0009450B1/fr
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G21C17/06—Devices or arrangements for monitoring or testing fuel or fuel elements outside the reactor core, e.g. for burn-up, for contamination
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/29—Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
    • G01T1/2914—Measurement of spatial distribution of radiation
    • G01T1/2964—Scanners
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • the present invention relates to a gamma radiation detector for controlling combustible needles.
  • This gamma radiation detector makes it possible to detect, in needles or fuel rods for nuclear reactors and which consist of a stack of fuel pellets, the presence of certain plutonium oxide and / or uranium pellets, the plutonium content of which and / or uranium would be out of specification.
  • the fuel in nuclear reactors of the "fast neutron” type, is in the form of needles each consisting of a stack of pellets of mixed uranium and plutonium oxide; in nuclear reactors of the "water reactors” type, the nuclear fuel is in the form of rods each consisting of a stack of enriched uranium oxide pellets. It is important to control the plutonium and / or uranium contents of these different pellets because this content conditions the proper functioning of the reactors and ensures obtaining high performance. It is essential for this that the pencils or the needles have a homogeneous distribution of uranium or plutonium; these pencils or these needles must therefore be checked tablet by tablet, which requires very high detection sensitivity.
  • Two methods can be used to control using gamma radiation detectors, combustible needles: on the one hand, a so-called “passive” method when the control is carried out using gamma radiation specific to the fuel, and on the other share a so-called “active” method in which the control is carried out using gamma rays emitted after irradiation of the fuel with neutrons.
  • this detector comprises an annular scintillator, associated with photomultipliers.
  • This annular detector is centered on the fuel rod or needle which passes through the detector by means of automatic transport, either directly in the case where the control uses the passive method, or after crossing an irradiator in the case where the control uses the active method.
  • the photomultipliers which are generally three in number, are regularly distributed around the periphery of the scintillator and are connected to measuring means, constituted by a fast counting electronics which records the pulses emitted by the photomultipliers at a rate of the order of 20,000 to 30,000 pulses per second for the passive method, and around 300,000 pulses per second for the active method.
  • the annular scintillator is associated with a collimator whose opening is adjustable according to the length of the pellets to be checked.
  • the geometry of the annular-shaped scintillator makes it possible to detect with a high control rate, a pellet whose content of fissile material (plutonium and / or enriched uranium) is out of specification. Too high a content entails a risk of local fusion of the fuel and rupture of the cladding which surrounds it. Too low a content decreases the thermal performance of the fuel needle.
  • this annular geometry makes it possible to avoid rejection of a needle or a pencil, all the pellets of which have a correct uranium and / or plutonium content.
  • the quality of the control carried out using these detectors essentially depends on the stability of the gain of the photomultipliers associated with the scintillator.
  • the gain of the photomultipliers undergoes a large fluctuation; it follows that the output signals from the photomultipliers exhibit significant deformation and that their amplitude is no longer proportional to the energy of the incident gamma photons.
  • capacitors are placed in parallel with the last resistors of the divider bridge which supplies the dynodes of the photomultipliers. However, it takes a certain time for each capacitor to recover its charge after having played its role of stabilizer.
  • each photomultiplier since the scintillator of annular shape consists of a single piece, a packet of light photons can be seen by several photomultipliers.
  • each photomultiplier operates with a very high counting rate and that thus any gain stabilization device connected to the divider bridge supplying the dynodes of the photomultipliers, cannot suppress completely the fluctuation caused by a sudden and significant variation in the number of incident gamma photons.
  • the spectrum observed on a photomultiplier has a significant altered energy resolution ration; this alteration is caused by the absorption, which varies depending on the path, of a certain number of light photons in the crystal constituting the scintillator.
  • the object of the present invention is to remedy these drawbacks and in particular to produce a gamma radiation detector for combustible needles making it possible to prevent a single packet of light photons from being able to be picked up by several photomultipliers. This results in a considerable reduction in the gain fluctuations of the photomultipliers, the reduction in the flow rate of the divider bridge connected to each photomultiplier as well as an improvement in the energy resolution of the detector.
  • the subject of the invention is a gamma radiation detector for controlling combustible needles, comprising an annular scintillator associated with photomultipliers connected to measuring means, characterized in that the annular scintillator is divided into sectors which are optically isolated from each other. others, each of these sectors being equipped with a photomultiplier.
  • the gamma radiation detector further comprises an annular diaphragm capable of collimating the radiation coming from each pellet contained in the controlled combustible needle.
  • the diaphragm has an adjustable opening.
  • the annular scintillator is a sodium iodide scintillator, activated with Thallium.
  • the scintillator sectors are optically isolated by a layer of alumina.
  • the sectors are identical.
  • the scintillator and the diaphragm are located in a shielded enclosure for protection against gamma radiation external to the detector.
  • a gamma radiation detector for combustible needles for known type, along a plane perpendicular to the axis of this detector.
  • This detector of known type comprises a scintillator 1, of annular shape, associated with photomultipliers 2, 3, 4.
  • This detector makes it possible to control the plutonium and / or uranium content of a nuclear fuel in the form of a pencil or needle 16, consisting of a stack of pellets of uranium oxide and / or plutonium oxide fuels. It also includes a diaphragm or collimator 6, the shape of which will be better specified with the aid of FIG.
  • the photomultipliers 2, 3, 4, the number of which has been limited to three, are regularly distributed around the periphery of the annular scintillator 1 and their outputs are connected to electronic measuring means. It is obvious, however, that the photomultipliers can be distributed differently.
  • the electronic measuring means which have not been shown in detail generally include electronic pulse counting circuits, associated with a plotter or a printer as well as a computer.
  • a packet of gamma photons such as 8 or 9, resulting from the emission of gamma radiation by a patch of the needle 16 can be picked up by several photomultipliers.
  • the packet 8 of gamma photons can be picked up by the photomultipliers 2, 3 while the packet 9 of gamma photons can be picked up at the same time by the three photomultipliers. This therefore results in the drawbacks already mentioned above.
  • This detector comprises a scintillator of annular shape 1, divided into identical sectors 10, 11, 12, optically isolated, and to which the photomultipliers 2, 3, 4 respectively correspond; this scintillator is preferably of the sodium iodide type, activated with Thallium; the different sectors of the scintillator are optically isolated by layers 13, 14, 15 of an optical insulator such as alumina.
  • An annular diaphragm 6 makes it possible to collimate the radiation coming from a pellet of the combustible needle 16 so as to limit the flux of the emitted radiation to approximately the length of this pellet.
  • the outputs of the photomultipliers are connected to measuring means 7, constituted for example by electronic counting circuits associated with a plotter or a printer as well as with a computer, not shown.
  • the diaphragm 6 is, as will be seen later, a diaphragm with adjustable opening, annular shape.
  • This detector is enclosed in a shielded enclosure for protection against gamma radiation external to the detector; this enclosure is not shown in the figure, it will be described later in detail.
  • the different sectors of the scintillator 1 are separated optically by layers 13, 14, 15 of an optical insulator such as alumina, which prevent a packet of gamma photons resulting from the radiation emitted by a pellet from being picked up by several photomultipliers at the same time. As seen above, this avoids large fluctuations in the gain of the photomultipliers and improves the energy resolution.
  • Sectors 10, 11 and 12 of the scintillator may not be identical.
  • FIG. 3 With reference to fig. 3 is shown schematically the detector of FIG. 2, shown in a shielded enclosure 15 ′ protecting it against external gamma radiation which could disturb the measurements.
  • This detector is shown in section, along a plane parallel to its axis. The same elements have the same references in this figure and in FIG. 2.
  • the 15 'shielded enclosure is a thick lead enclosure.
  • the measurement means connected to the photomultipliers 2 and 4 have not been shown in this figure. As indicated above, this detector allows the control of a needle or a pencil 16 by measuring gamma radiation. emitted by the nuclear fuel pellets 5 contained in a cladding 17.
  • the diaphragm 6 consists of two annular parts 19, 20 opaque to gamma radiation; these parts have a spacing e which can be adjusted by means not shown, depending on the length of the pads 5 to be checked. These two parts opaque to gamma radiation make it possible to limit the flux of gamma rays emitted towards the scintillator 1 to approximately the length of a patch. of the detector.
  • the possibility of adjusting the aperture e of the diaphragm 6 makes it possible to be placed in optimal conditions corresponding to a compromise between the length of the pellets and the control rate.

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  • Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
  • Measurement Of Radiation (AREA)
  • Monitoring And Testing Of Nuclear Reactors (AREA)
EP79400652A 1978-09-25 1979-09-18 Détecteur de rayonnements gamma pour le contrôle d'aiguilles combustibles Expired EP0009450B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7827348 1978-09-25
FR7827348A FR2437002A1 (fr) 1978-09-25 1978-09-25 Detecteur de rayonnements g pour le controle d'aiguilles combustibles

Publications (2)

Publication Number Publication Date
EP0009450A1 EP0009450A1 (fr) 1980-04-02
EP0009450B1 true EP0009450B1 (fr) 1981-12-09

Family

ID=9212990

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79400652A Expired EP0009450B1 (fr) 1978-09-25 1979-09-18 Détecteur de rayonnements gamma pour le contrôle d'aiguilles combustibles

Country Status (6)

Country Link
EP (1) EP0009450B1 (enrdf_load_stackoverflow)
JP (1) JPS5545000A (enrdf_load_stackoverflow)
CA (1) CA1147068A (enrdf_load_stackoverflow)
DE (1) DE2961556D1 (enrdf_load_stackoverflow)
ES (1) ES484440A0 (enrdf_load_stackoverflow)
FR (1) FR2437002A1 (enrdf_load_stackoverflow)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8415476D0 (en) * 1984-06-18 1984-07-25 British Nuclear Fuels Plc Inspection apparatus
FR2782562B1 (fr) 1998-08-18 2000-09-29 Cogema Procede de simulation de la reponse d'un detecteur de rayonnements emis par des objets radioactifs et procede de controle d'elements de combustible nucleaire utilisant cette simulation
AU2003254422A1 (en) * 2003-07-23 2005-02-04 Belgonucleaire Sa Method and apparatus for controlling the homogeneity of mox fuel pellets
RU2296352C1 (ru) * 2005-11-22 2007-03-27 Закрытое акционерное общество "ИНТРА" Сцинтилляционное детектирующее устройство
JP2007240357A (ja) * 2006-03-09 2007-09-20 Nuclear Fuel Ind Ltd 燃料棒の表面汚染密度の自動検査装置と検査方法
FR2913140B1 (fr) * 2007-02-27 2016-08-19 Cie Generale Des Matieres Nucleaires Dispositif et procede d'examen de crayons cylindriques de combustible nucleaire
FR2945373B1 (fr) * 2009-05-05 2014-06-06 Realisations Nucleaires Sa D Et Dispositif et appareil pour la mesure du profil d'enrichissement d'un crayon de combustible nucleaire
CN109343100B (zh) * 2018-10-11 2024-07-05 中国科学院高能物理研究所 一种放射性材料的检测装置

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1912982A1 (de) * 1969-03-14 1970-10-01 Interatom Vorrichtung zur zerstoerunsfreien und getrennten Bestimmung der Konzentrationen spaltbarer Stoffe in einem Pruefkoerper
AT344830B (de) * 1976-01-21 1978-08-10 Interatom Verfahren und vorrichtung zur messung der spaltstoffkonzentration in fluessigmetallgekuehlten brennelementen
JPS52102891A (en) * 1976-02-25 1977-08-29 Doryokuro Kakunenryo Fluorescent substances for scintillation detectors

Also Published As

Publication number Publication date
DE2961556D1 (en) 1982-02-04
JPS5545000A (en) 1980-03-29
FR2437002A1 (fr) 1980-04-18
FR2437002B1 (enrdf_load_stackoverflow) 1981-07-10
CA1147068A (en) 1983-05-24
EP0009450A1 (fr) 1980-04-02
ES8103846A1 (es) 1981-02-16
JPS649596B2 (enrdf_load_stackoverflow) 1989-02-17
ES484440A0 (es) 1981-02-16

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